Effects of recombinant human growth hormone (r-hGH) on experimental osteoporotic fracture healing

Objective:: To observe the effect of recombinant human growth hormone (r-hGH) on osteoporotic fracture healing in rats, and to provide an effective therapy for osteoporotic fracture. Methods: Thirty-six female 8-month-old SD rats were randomized into two groups: therapy group and control group. After the experimental model of osteoporotic fracture was established, the therapy group was treated with r-hGH of 2.7 mg/kg body weigh/day (1 mg=3 IU) for 10 days continuously by daily subcutaneous injection; whereas the control group was treated with equivalent saline. Plasma insulin-like growth factor I concentration was detected and bone mineral density (BMD) as well as biomechanical strength of callus were measured at 2, 4, 8 weeks. Results: Plasma insulin-like growth factor I concentration in the therapy group was higher than that in the control group (P< 0.005 ) at 2nd week and began to decline at 4th week. At 8th week, there was no significant difference between the two groups. At 4th week, callus area and BMD in therapy group were higher than those in the control group, but at 8th week, they were lower and BMD had a significant difference between the two groups (P< 0.001 ). Biomechanical testing of callus showed that torsional strength of the therapy group was higher than that of the control group at 4th or 8th week, meanwhile maximum torsional angle had a significant difference between the two groups (P< 0.005 ).Conclusions: The results show that exogenous r-hGH can stimulate osteoporotic fracture healing in rats.